BACKGROUND: Ultraviolet B generates reactive oxygen species by interacting with water in irradiated skin tissues and cells in turn causes lipid peroxidation, protein modification and further DNA damage.PURPOSE: This study examined the cytoprotective effects of phloroglucinol (1,3,5-trihydroxybenzene) on ultraviolet B-irradiated cultured human keratinocytes.METHODS: The human keratinocyte cell line HaCaT cells were treated with 10 μM of phloroglucinol. After 1 h, the cells were irradiated with ultraviolet B light at 30 mJ/cm(2) and incubated at 37°C.RESULTS: Phloroglucinol scavenged both the superoxide anion and hydroxyl radical in a cell-free system and ultraviolet B-induced intracellular reactive oxygen species. Phloroglucinol reduced ultraviolet B-generated lipid peroxidation, protein modification and DNA strand breaks. The enzymatic effects of phloroglucinol restored cellular glutathione levels, superoxide dismutase and catalase activities, which were impaired by ultraviolet B radiation.CONCLUSION: Phloroglucinol provides the protective effects in human keratinocyte cell line exposed to ultraviolet B radiation, suggesting that phloroglucinol can be used as a photoprotective agent.